1. Technical Field
The present invention relates to a flexible bag or package with walls made up of multi-layer thin films wherein a section of at least one layer of said multi-layer film can easily be removed without compromising the barrier properties of said bag. In particular, the removable section is adhered to the package at an initiation area having a lower peel force to more easily facilitate initial removal and a remaining area having a higher peel force.
2. Description of Related Art
Flexible bags are commonly used for packaging. For food packaging, in particular, flexible bags with walls made up of multi-layer flexible films and specific barrier properties are common for containing foods such as chips, popcorn, nuts, or cereals. It is also common for promotional devices to accompany all types of packaging, including paperboard, cardboard, and polymer and other flexible thin film packaging. Such devices may be incorporated into packaging any number of ways.
U.S. Pat. Nos. 6,251,450 ('450) and 5,127,743 ('743) disclose food packages with walls comprised of multi-layer of flexible films wherein a promotional device is sealed between layers of the multi-layered package wall.
The '743 patent discloses a method of forming a package comprised of multi-layer flexible films wherein a promotional device is printed on the inside surface of one of the outer layers of the package. The promotional printed indicium is only partially visible from the outside of the package and is accessed by puncturing the outer layer of the package and separating the inner layer from the outer layer containing the hidden indicia. This separation is possible because no adhesive is applied between the portion of the outer layer containing the printed hidden indicia and the next innermost layer of the container.
As illustrated by the '450 and '743 patents, when promotional devices have been incorporated into flexible plastic bags composed of thin films in the prior art, the devices are not conveniently accessible to the consumer. The devices are generally either placed inside the bag along with the product, or embedded between the layers of the bag and sealed in place by an adhesive such that the bag must be cut, torn, or punctured in some way in order to gain access to the device. FIG. 1 is one example of this type of design and is a view of a cross-section of the wall of a package that incorporates a promotional device. The wall includes an outer layer 18 and an inner layer 20. Hidden printed indicia 24 are incorporated into the conventional printed layer 22, and both are printed on the inner facing side of the outer layer 18. The hidden printed indicia portion 24 consists of a series of printed ink layers 26, 28, 30, which includes a layer containing the promotional device 30, and printed layers 26, 28 that reveal the existence of the promotional device but obscure its exact nature when viewing from outside the package. The outer layer 18 is attached to the inner layer 20 by an adhesive layer 32. The adhesive layer 32, however, is not applied in the area where the hidden printed indicia portion 24 contacts the inner layer 20. When the outer layer 18 is cut or punctured to access the promotional device 24, this permits the portion of the outer layer 18 containing the device 24 to be separated from the inner layer 20 and viewed directly.
One problem with designs such as the '743 and '450 patents is that the cutting or tearing necessary to access the promotional device sacrifices the container's functional characteristics. The necessity of additional manufacturing steps is also a drawback of designs that place the promotional piece either inside the package or between the walls of the package. The additional steps greatly increase operating, material, and defect costs. Furthermore, if a promotional prize is inadvertently left out of a container, such process errors are likely to go undetected and have often ultimately lead to customer complaints.
U.S. Pat. No. 4,345,393 ('393) is one of many examples in the prior art where promotional devices are incorporated into packaging. The '393 patent discloses a two-ply, erect, paperboard or cardboard carton. In a defined section of the outer ply of the carton, slits/perforations are cut to outline a desired size and shape such that the defined section may be torn along the slits/perforations and removed from the carton without disturbing the integrity of the rigid inner ply.
Another example of an invention where a promotional device is incorporated into packaging is U.S. Pat. No. 5,021,274 ('274). The '274 patent discloses a two-ply, erect, paperboard or cardboard container, including a corrugated inner ply and an outer ply incorporating a removable section outlined by a perforated die cut. The perforated die cut allows the removable section to be torn away from the package while leaving the corrugated inner ply intact.
As demonstrated by the '393 and '274 patents, promotional devices have also been incorporated into the walls of containers other than flexible bags, such as erect paperboard cartons or boxes. In some of these designs, the promotional device may be accessed without compromising the functional characteristics of the container. In others, however, removal of the device results in a hole in the container. FIG. 2 is an example of a container design wherein a promotional device is incorporated into the outer ply of a two-ply erect carton constructed from paperboard or cardboard. The integrity of the carton is not compromised upon accessing the device. In this embodiment, the outer ply 52 of the box is bonded to the inner ply by an adhesive layer 60. The promotional device is in the form of a detachable coupon 63 that is a portion of the outer ply 52. The coupon 63 is outlined by perforated slits 64 in the outer ply 52 that permit the coupon 63 to be removed by tearing along said perforated line 64. The coupon 63 portion of the outer ply 52 does not adhere to the inner ply because the inner side 66 of the outer ply 52 corresponding to the coupon 63 is coated with an adhesive-repelling agent. Employment of the adhesive-repelling agent and perforated tear outline 64 in combination permit the coupon 63 to be torn from the container.
One drawback of a design similar to the one illustrated by FIG. 2 is that perforated lines do not always tear cleanly, and as they are torn are prone to snagging and causing undesired tearing outside the perforated lines. Such unwanted tearing of the package or promotional device outside the perforated line may reduce the aesthetic value of any designs on the package or promotional device. In addition, depending on the type of promotional device, such unwanted tearing of the device may reduce its redeemable value and/or its value to a consumer.
The designs of the '393 and '274 patents also require that the container be in the form of an erect carton assembled from paperboard or cardboard materials. They do not contemplate important improvements in packaging material technologies, such as use of polymeric, multi-layered, flexible thin films. These newer materials are stronger and more flexible per unit of material than paper, paperboard, or cardboard-type packaging materials pertinent to the '393, '274 designs. Additionally, thin-film packaging materials, such as employed in packaging some snack foods, are orders of magnitude thinner and less bulky than their cellulose product counterparts. In many applications, these differences and improvements in dimensional and functional characteristics of packaging materials render the older wood-based materials useless. In addition, the drastic differences in physical characteristics between flexible thin films and wood-based packaging materials present drastically different processing problems, and require significant development to optimize effective thin film packaging.
One solution to address these problems is disclosed in U.S. Pat. No. 6,746,743, assigned to the same assignee as the present invention, and is hereby incorporated by reference. FIG. 3 is a perspective view of an embodiment of this prior art reference wherein a removable promotional piece is designed into the outer layer of a container and is outlined by a continuous cut 60. The '743 patent discloses a multi-layer flexible thin film container having a constant degree of releaseable adherence across the surface of the container. A continuous cut 60 penetrates the outer ply to permit the portion of the outer ply 70 bounded by the continuous cut 60 to be removed from the container. The releasable adherence provides a peel force to sufficiently adhere the outer ply 70 to the container such that the outer ply 70 is not removed during normal shipping and handling operations. To initiate removal, the peel force provided by the releasable adherence must be overcome. One drawback of this invention is the potential difficulty in overcoming the peel force to initiate removal of the outer ply 70. Further, it may be desirable to strengthen the peel force to prevent inadvertent removal of the outer ply 70 while still permitting easy initiation.
Consequently, there is a need for an improved container with enhanced barrier characteristics due to its construction from polymeric multi-layer flexible films. The container should provide an easier way to initiate removal of the removable piece. The container should also permit a stronger releasable adherence to be applied to selected portions of the package. The removal of the device from the package should not result in damage to the device itself or the package. Furthermore, removal of the device should not compromise the advanced barrier characteristics of the package.